Fast portscan detection using sequential hypothesis testing
Jaeyeon Jung
Paxson, V.
Berger, A.W.
Balakrishnan, H.
Comput. Sci. & Artificial Intelligence Lab., MIT, USA;
This paper appears in: Security and Privacy, 2004. Proceedings. 2004 IEEE Symposium on
Publication Date: 9-12 May 2004
On page(s): 211- 225
ISSN: 1081-6011
ISBN: 0-7695-2136-3
INSPEC Accession Number: 8065997
Digital Object Identifier: 10.1109/SECPRI.2004.1301325
Current Version Published: 2004-06-01
Abstract
Attackers routinely perform random portscans of IP addresses to find vulnerable servers to compromise. Network intrusion detection systems (NIDS) attempt to detect such behavior and flag these portscanners as malicious. An important need in such systems is prompt response: the sooner a NIDS detects malice, the lower the resulting damage. At the same time, a NIDS should not falsely implicate benign remote hosts as malicious. Balancing the goals of promptness and accuracy in detecting malicious scanners is a delicate and difficult task. We develop a connection between this problem and the theory of sequential hypothesis testing and show that one can model accesses to local IP addresses as a random walk on one of two stochastic processes, corresponding respectively to the access patterns of benign remote hosts and malicious ones. The detection problem then becomes one of observing a particular trajectory and inferring from it the most likely classification for the remote host. We use this insight to develop TRW (Threshold Random Walk), an online detection algorithm that identifies malicious remote hosts. Using an analysis of traces from two qualitatively different sites, we show that TRW requires a much smaller number of connection attempts (4 or 5 in practice) to detect malicious activity compared to previous schemes, while also providing theoretical bounds on the low (and configurable) probabilities of missed detection and false alarms. In summary, TRW performs significantly faster and also more accurately than other current solutions.
Index
Terms
Available to subscribers and IEEE members.
References
Available to subscribers and IEEE members.
Citing Documents
Available to subscribers and IEEE members.
Cart
